Matter Definition and 1000 Threads

Dear Friends! I have read that in early universe in the inflationary phase the average density of matter was equal to critical density and now it is 10 percent of that due to which it is probably inferred that there must be hidden dark matter. Please correct the information if wrong or...

I got a question in my mind as to how the tiny dot of matter during the big bang contained so much energy that could create the universe. Remember this tiny dot contained so much energy that it could transform this energy into matter in the form of the universe (Remember E=MC2). The Quantum...

One of the sources of matter creation is pair production when 2 gamma ray photons collide and produce electron positron pair. The other would be Quantum Fluctuations which create again electron-positron pairs. What are the other methods of matter creation other than the above two?

How paul dirac find antimatter equation I guess It came this equation E2=(pc)2+(mc2)2 than we pass E2=(mc2)2 than E=mc2 and -E=mc2 isn't it ?

http://arxiv.org/pdf/1409.6302.p It is argued in this paper that Dark Matter does not exist, what do you think.

after watching minutephysics video on breaking the speed of light with a laser pointer (kinda a cheat though, as you are not actually making anything move faster than light.) I came to wonder, what if instead of using beam a light and the image it creates to appear faster. you instead used an...

Dear Forum, Vacuum is classically interpreted as the absence of everything. But the quantum view of vacuum sees it as a bubbling, dynamic entity from which particles and antiparcles emerge for very short intervals of time. Relativity teaches us that energy and matter can be converted into each...

Hi All, One gets homological/topological information (DeRham cohomology ) from a manifold by forming the algebraic quotients H^Dr (n):= (Closed n-Forms)/(Exact n- Forms) Why do we care only about closed forms ? I imagine we can use DeRham's theorem that gives us a specific...

Hi Guys, Can anyone provide links, books which explain the mathematical background of the field theory that explains the current accepted ^CDM model of the universe? Thanks Adarsh

Everyone learns the picture associated with e.g. the Balmer series in Hydrogen: a photon with a precise energy flies in and is absorbed by an electron which is excited into a higher energy state, which then decays to the ground state, re-radiating a photon of that precise frequency. If we...

If dark matter affects normal matter (by gravity), does that mean that normal matter also affects dark matter? I think it does... In which case; Black holes could attract BOTH dark and normal matter? Does this give any opportunity to "information loss"? What if some information in normal...

Im wondering if motion can be turned into matter, since I heard that motion is like stored energy. Im not in any physics classes so I don't really know anything about the subject. edit: I am also wondering if this is true: Energy is effected by gravity, and movement is stored energy. So if a...

Light traveling transverse to a massive body (e.g. Sun) is deviated by an angle twice the amount predicted by Newtonian gravitational theory. This is predicted by GR and proven experimentally. What would be the deviation of a matter particle traveling near c transverse to a massive body...

Why isn't the dark matter just randomly distributed? How does it know where to go? Why does the amount of dark matter increase the further away from the galaxy's center?

So the universe is expanding, rather space is expanding. By expanding we mean space is coming into existence at all points. Is that an equal rate of expansion everywhere? Now the expansion does not over come the force holding matter together, planetary systems, galaxies even galactic...

I've been working with NFW Dark Matter Halos recently. This is a particular density model for the halo developed by Navarro, Frenk, & White (NFW). The density structure has the form \rho (r) = \frac{\delta_c \rho_c}{(r/r_s)(1+r/r_s)^2} where \delta_c = \frac{200}{3}...

Hi all It may sound rather silly, but I am a second year graduate student doing experimental condensed matter physics. Recently I've been thinking about the future like job aspects and salaries etc. One of my friend recently transferred to medical physics PhD and said its better in job...

Hello fellows, Properly introducing myself into dark matter so in the quest for book suggestions from those of you who are into the topic. Thanks in advance

Hi I am curios about something we know E2=(mc2)2+(pc)2 than Paul Dirac maid E2=(mc2)2 than we know he find antimatter I want to said there's a chance to E=-pc because its logical you can say photon and antiphoton is same but I think there's no reason to say this is false.

Having completed my undergraduate degree in Physics, I was pressed to take a Ms immediately after. Despite my aspirations, since it was not a good time for me and it was difficult for me to study, I decided to take an address, "physics of matter", that is less prestigious than "theoretical...

While reading about von Mises distributions I wondered if the distribution of clusters such as galaxies could be related to the way they are being "mapped". Suppose we observing our universe from a particular perspective, perhaps described by something like a von Mises distribution, or other...

Is energy of the wave solely based on frequency? I know E=hf. Is energy of matter based on E=mc^2?

Most people come up with their own internal reasoning for things like this that have not been explained. I was curious on the community's various opinions and theories on this subject. I think it would be a fun exercise to help each other evolve our own theories on things like this. Standard...

Dark matter can't radiate heat (i.e. no electromagnetic energy). 1. Might it retain the original temperature at the moment of its creation? 2. If temperature is directly related to pressure and both are inversely related to volume, then would cosmic expansion mean that dark matter is as...

For school my teacher told me there were 3 states of matter but the internet told me there were 5. Help?

Hi guys, I have a bachelor's degree in IT (software development, BAC+3), I am 27 years old and I live in Europe. I've always love space and astrophysics but I am interested in physics in general. I decided to go back to school to get a degree in physics but I am not quite sure about which...

I have been thinking for the past couple months on how the expansion of the universe effects the matter and energy within it. Please read every line, skipping any part of this thread will lead to confusion. Hopefully someone can shed some light on this amazing new question of universal expansion...

1. Gravity is the geometric curvature of space-time caused by massive objects. 2. Dark Matter surrounds galaxies. 3. Dark Matter is thought to be critical in galaxy formation. 4. The mass of Dark Matter creates curvatures in space-time around baryonic matter which forms galaxies. What roles...

To whom is able to answer this: I think that when radiant energy get in contact with matter three basic phenomena take place: 1.- Transmission 2.- Reflection 3.-Absorption and emission I think this three basic phenomena enclose all phenomena that can occur after the interaction I wait for...

I was really wondering if the number of blades in a propeller influenced the power it has, are too many blades bad also? At last I will like to know how much force will you need to elevate a person 1 meter over the ground an mantain the person at that height?

If matter and anti matter can combine to cancel each other out, can your reverse the process to pull matter and anti matter from nothing? I ask in a theoretical sense, not weather we are currently capable or not. Looking forward to your responses!

Hey, guys! I'm a ME major and I am going into my second year (I know, gen. ed and copious amount of math classes lol). Anyway, I am currently attending UNLV and I've heard that it isn't a "good" school for ME. I am very motivated and I strive for a high GPA and I will be looking into...

If so, what about smells coming from solid matter, like wood?

Hi everyone, I have a few questions about relativity. I've been reading about relativity and its effects and I began to wonder at what point does it become a variable worth mentioning? Suppose there were 3 solar systems each with an Earth that revolved around the sun. Earth 1 does not...

dear friends, I have always wonder: is there a smallest unit for time and matter? or in other words, can we continuesly divide time and matter into smaller pieces non-stop? ive had this question since young when I imagined myself cutting a piece of cheese. I just can't help stop cutting it and...

Dark Matter constitutes 26.8% (wikipedia) of the observable universe. So where is it? I ask this question because although it is said to be not visible. It must interact with light matter at a gravitational level. It only makes sense to me that dark matter must be all around us and...

Can a plasma be compressed to greater densities than other forms of matter?

I'm not a physicist nevertheless I wonder about these things so here goes: On wikipedia I read that the universe contains: 68.3% Dark energy 26.8% Dark matter 4.9% Normal matter But I wonder why normal (light energy) is not mentioned here. Since the beginning of the universe a lot of light...

Is matter and energy the same thing?Is energy something that "is there" or is it just a description of matter, like the term speed?

Homework Statement Hello, I am preparing a condensed matter exam and I was wondering if I could get some help on the following question from a past exam paper: Show that for the free electron gas at zero temperature the Fermi energy is given by: ε_{F}=\frac{\hbar^{2}}{2m}(3π^{2}N)^{2/3} and...

De broglie had proposed that matter had wave character. Which wave does he mean? Transverse or longitudinal?

This quantum vacuum thing... I'm thinking about these virtual particles popping in and out of existence. Does that happen everywhere including inside atoms(within electron orbitals), protons, quarks and whatever is smaller? Or just in the space between Atoms... what i would call vacuum? im a...

Homework Statement A two component gaseous system has a fundamental equation of the form S=AU1/3V1/3N1/3 + (BN1N2)/N N=N1+N2 where A and B are positive constants. V is volume , S is entropy, U is internal energy, N is mole number. A closed cylinder of total volume 2V0 is separated into two...

Is the amount of Dark Matter in a Galaxy equal the amount of Matter consumed by all the Black Holes in that Galaxy?

I'm not sure if we can. We can see it, but are we actually sensing matter when we see it, or just light?

Can string theory explain dark matter and dark energy?

Hi, I am a research student in Theoretical Dark Matter Cosmology. I am currently working on the evolution of dark matter WIMP in the early universe. I am trying to understand how to derive the famous condition for dark matter decoupling,T = m/26. How do you get this condition from the...

Depending on who one asks and their interpretation of QM, entanglement seems to be either: a) No problem at all. It's just a matter of information. If you knew one entangled electron was spin up, then the other must have been spin down by inference of the prepared state of the system. b)...

It's just this one class I'm taking. It's really, really demoralizing. I normally do pretty well in my classes, I'm majoring in electrical engineering and I've so far kept a 3.2 GPA. I've only had to repeat one class, calculus II, and that was over a year ago, all of my other math classes I...

Is the ratio of matter to radiation density constant in the universe? Or does it vary over time, as matter annihilates to radiation and vice-versa?